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Roanoke logperch

Roanoke logperch
Conservation status
Vulnerable (IUCN 3.1)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Perciformes
Family:	Percidae
Genus:	Percina
Species:	P. rex
Binomial name
Percina rex

The Roanoke logperch (Percina rex) is a small freshwater fish found in the Roanoke River Basin of Virginia and North Carolina in the United States. It inhabits warm, clear, medium-sized rivers in runs, pools, and riffles with gravelly or rocky bottoms. It is primarily insectivorous. This fish is a federally listed endangered species.

Description

The Roanoke logperch is a type of darter fish. Adults are between 80 and 115 mm SL; individuals can grow up to 5.5 inches long (14 cm). The elongated body is dark-green to yellowish in color with a white belly. There are prominent dark, vertically elongated bar markings on the sides of the body that are ovoid in shape. The first of two dorsal fins features an orange to orange-red band that is particularly prominent in males. Both dorsal fins, as well as the tail fin, have dark markings, while the pelvic and anal fins are pale. The large eyes are located near the top of the head. The fish has a long, conical snout with a bulbous or blunt tip. The mouth is inferior, meaning the lower jaw is shorter than the upper jaw.

Range and Distribution

The Roanoke logperch is non-migratory and is found almost entirely in southern Virginia, within the Roanoke River Basin. Its habitat includes the upper reaches of the Roanoke, Chowan, and Dan River systems. As these rivers all flow southeasterly, the Roanoke logperch has also been found in North Carolina, though only a few miles south of the Virginia state border. For a range map, see the species' page on the IUCN website.

The species is not made up of one contiguous population. The installation of dams fragmented the species' habitat, resulting in eight known discrete populations: 1) the upper Roanoke River downstream to Niagara Dam, 2) the middle Roanoke River downstream of Leesville Lake, 3) the upper Pigg River upstream of Power Dam, 4) the middle Pigg River downstream of Power Dam, 5) the Smith River upstream of Philpott Reservoir, 6) the Smith River downstream of Philpott Reservoir down to the headwaters of Martinsville Dam, 7) the Smith River downstream of Martinsville Dam, and 8) the Nottoway River system. The largest of these is the upper Roanoke River population. Though these discrete populations have been identified, the total number of individuals overall is not known. As it is difficult to gain information about the abundance and density of this particular species, there have been few attempts to gather this data, and therefore very little is known.

History

The Roanoke logperch was first recorded in 1888 by D. Jordan and B.W. Evermann, when it was found in the Roanoke River. It was initially named Etheostoma rex until later placement in the Percina genus. It is possible that the species originated in logperch stock that dispersed from the adjacent New River Basin to the Roanoke River Basin. Prior to European settlement in the area, it is likely that the species was well-connected throughout the Roanoke and Chowan River systems, which is no longer the case. There is generally low genetic divergence between the current populations, supporting the theory that a larger, more integrated population was fragmented in the last 200 years. Full understanding of the historic connections between the smaller discrete populations would require more genetic information than is currently available.

Habitat and Behavior

The Roanoke logperch inhabits small to medium rivers of low to moderate gradient, where it is found in runs, pools, and riffles. It lives in sandy, stony, or boulder-strewn areas, and is intolerant of moderate to heavy presence of silt. It is suggested that this fish also prefers areas with woody debris. During the reproductive period, males are found more in shallow riffles, while females are found more in deep runs. Young individuals usually gather in mixed-species schools, though individuals of all ages have been observed as part of these schools.

Individuals are sexually mature by about two to three years of age. Spawning occurs from mid-April to early May in water that is 12-14 °C (54-58 degrees Fahrenheit). After spawning, the eggs are buried and the adult fish are not involved in the care of offspring following this event. Observations of negatively impacted populations suggest that dispersal plays a role in the species' population dynamics. However, not much is known about this behavior; drifting larvae may play a role. An individual's entire life cycle is typically five to six years.

The Roanoke logperch's conical snout is important to its feeding habits. It uses its snout to turn over gravel and rocks in riverbeds, and feed on exposed invertebrates, primarily larvae. It has also been observed flipping over wood and bark to search for food. This foraging behavior enables them to reach prey sheltered beneath rocks that may be unavailable to other benthic fishes; however, it relies on the availability of loosely embedded substrate. Although this is the main method by which the Roanoke logperch feeds, it will eat most food it encounters, and has been observed feeding above the riverbed and grazing.

Conservation

Threats

A variety of threats have affected and continue to affect the Roanoke logperch. It is thought that the species has likely declined over the last 200 years, however, lack of knowledge of historical numbers makes it difficult to determine long-term population trends. There is currently no evidence that suggests that natural predators or disease threaten the species; therefore, the decline and current threatened state is likely due to anthropogenic impacts.

As previously noted, Roanoke logperch are generally intolerant of moderate to heavily silted substrate. Siltation destroys eggs and larvae, reduces access to loose substrate, and compromises visibility of sight predators such as the Roanoke logperch. The threat posed by silt input likely started the population decline, once human settlement began in the Roanoke River Basin area. This threat has become more prevalent as urbanization, agricultural activity, and road building has increased in areas around the species' habitat. The construction involved in all three of these activities increases silt runoff into bodies of water. Road building and urbanization convert ground surfaces to impervious surfaces, resulting in decreased water absorption. Agricultural activity causes erosion, all three of these activities compiling and dramatically increasing silt runoff in rivers and streams. These factors are also strongly correlated with the pollution issues that threaten species. Fertilizer runoff, chemical runoff, and toxic spills have all had negative impacts on Roanoke logperch populations. One of the most detrimental instances of this threat was the 1975 copper sulfate spill in the Pigg River that resulted in decimation of the logperch population in that area.

In the 1950s and 1960s, the species faced highly destructive consequences from the construction of dams in the Roanoke River Basin. Impoundment caused by dams destroys the species' habitat, flooding the river environment upstream of the dam and transforming it into a reservoir. Additionally, the physical barriers of dams impairs the species' movement through its habitat range. Historically, the most destructive of these developments was the 1966 completion of the Smith Mountain and Leesville Dams on the Roanoke River, destroying nearly 60 miles of habitat from impoundment. As discussed previously, the construction of dams is the purported primary cause of the fragmented Roanoke logperch populations.

If it is true that the Roanoke logperch prefers woody debris in its habitat, it is also likely that the species is affected by wood debris removal practices and deforestation of the riparian zone.

Listing and Recovery

The Roanoke logperch was first listed by the U.S. Fish and Wildlife Service (USFWS) under the Endangered Species Act (ESA) as "Endangered" on August 18, 1989. A recovery plan was produced by the USFWS in March 1992. This recovery plan aimed to downlist the species to "Threatened" within 15 years. The plan stipulated that reclassification could occur if each of the four discrete populations known at the time: 1) became stable or increasing, 2) was protected from threats, and 3) the Roanoke River and at least two other populations showed steadily increasing numbers and/or increased range. Several actions were proposed to achieve these objectives, including legislation, education initiatives, attempts to populate new and historical habitat, and management of existing populations. Research and monitoring that was conducted to support the plan's objectives were valuable byproducts of the recovery plan, as little was known regarding the Roanoke logperch populations prior to the creation of this plan. During the 15 years following the creation of the recovery plan, additional populations were discovered, ultimately adding up to the eight discrete populations that are known today. Despite expanding knowledge of the species, the recovery plan was not wholly successful. The first detailed five-year review of the species was carried out by the USFWS in summer 2007, 15 years after the release of the recovery plan, and did not downlist the Roanoke logperch from its "Endangered" status. The review concluded that it was not abundantly clear that the Roanoke logperch populations were stable or increasing, or if the restoration of 31 miles of habitat resulted in positive impacts on the populations. Additionally, the review determined that threats to the species were ongoing or increasing. Therefore, the criteria for reclassification were not met. Recommendations for future actions included focusing on the reduction of silt input into the species' habitat, increasing connectivity of populations, preventing toxic spills, and continuing to evaluate the feasibility of habitat for reintroduction. The review also noted the necessity for measurable criteria in an effective recovery plan, and recommended revisions to the recovery plan to include these.

Currently, there is great need for more research in order for the recovery of the species to be achieved. The data that has been collected and continues to be collected since the creation of the 1992 recovery plan will hopefully lay the foundation for clearer conclusions to be made in subsequent reviews of the species. However, more research and monitoring, including establishing efficient sampling methods, creating a population census, and better understanding of which habitats within river environments are critical to the species, would provide a better idea of how recovery can be attained.

Status

As of April 2012, the Roanoke logperch is rated by the IUCN as "Vulnerable." At the time of this listing update, the population was thought to be increasing overall. However, given the poor understanding of the true population count, this assessment is difficult to make. The Pigg River is the only known habitat area in which the logperch population is currently experiencing clear increase.

A new five-year review of the Roanoke logperch's status was initiated by the USFWS in August 2018. At this time, the USFWS had the the species listed as "Endangered."

Development of the Roanoke River Basin area continues, so the species will likely continue to face threats in the future.